term 1 - chemistry reactions, profiles and rates Flashcards
the number of protons and electrons in an element is the same as?
the element’s atomic number
how do you find the number of neutrons an element has?
atomic mass - atomic number
(1) all matter is composed of _____, and has ____ and ______?
atoms
mass
volume
(3) endothermic reaction?
heat energy is ‘absorbed’ and the temperature lowers
(3) exothermic reaction?
heat energy is ‘released’ during the reaction and the temperature increases
bonds of reactants have more energy than the products?
exothermic
energy difference is given out as heat
bonds of reactants have less energy than the products?
endothermic
extra energy is needed to form the product, which is taken from its surroundings, so the temperature falls
(2) signs of a chemical change?
temperature change
colour change
light emmited
fizz/bubbles/gas
precipitate/solid is formed
smell/odour
photosynthesis and respiration are _________?
opposites
photosynthesis is ___________ reaction?
endothermic
respiration is __________ reaction?
exothermic
how do you know that a chemical reaction involves oxygen/word equation for an element + oxygen?
you see something burn + the energy is released in the form of heat and light
not every substance reacts with oxygen in the same way
element + oxygen = oxide + energy
what happens when hydrogen burns in oxygen?
large amounts of heat are released, which can be dangerous in an uncontrolled environment
fuel?
substance that will have a large amount of useful energy quickly once it undergoes a chemical reaction
what do many fuels contain?
hydrocarbons
compounds of carbon and hydrogen
(4 and 5) combustion?
oxygen + often contains carbon and hydrogen. living things
exothermic reaction that occurs at different rates
produces heat or light energy
(4) what is corrosion?
When a metal is attacked by substances around it such as moisture, acids, etc.
eg. rust of iron
(4) what type of reaction is corrosion?
process involves oxygen and water therefore it is a form of combustion (non-living)
(9) what affect does temperature have on a reaction?
more heat = more speed = more collisions
particles turn heat into kinetic energy
(9) what affect does concentration have on a reaction?
more particles in same space = more collisions
(9) what affect does catalysts have on a reaction?
reduce activation energy needed for a reaction
less activation energy = more effective collisions = faster rate
(9) what affect does surface area have on a reaction?
increase in SA —> more collisions
more collisions = more effective collisions = faster rate
(9) activation energy?
minimum amount of energy to start a reaction
collision theory?
reactions do not happen unless particles are in contact and able to collide. particles are constantly moving.
